You only need to attend 3 meetings and have a proof of how you participated in these communities and will be enough to get a free ticket for the event, please ask the respective groups / technical communities.

But why the ticket price ?
"Since a couple of years, we have been tackling the problem of the people who would register at the events (SQLSaturdays, SharePointSaturday, Tuga IT, etc) and not appear at all. We had situations where well over 50% of the registered people did not appeared. "

Source : nikoport.com

And this has
resulted in a waste of food and the people who were on the waiting list
did not have the chance because the facilities have a visitor limit.

Fortunately, event volunteers are able to distribute excess food to Refood (www.re-food.org) so nothing is wasted.